﻿#region Using

using System;
using System.Text;
using System.Web;
using System.Text.RegularExpressions;
using System.Globalization;
using System.Collections.Generic;
using SubjectWorkShop.Core;

#endregion

namespace SubjectWorkShop.Core.Web.HttpModules
{
    /// <summary>
    /// Handles pretty URL's and redirects them to the permalinks.
    /// </summary>
    public class UrlRewrite : IHttpModule
    {
        #region IHttpModule Members

        /// <summary>
        /// 
        /// </summary>
        public void Dispose()
        {
            // Nothing to dispose
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="context"></param>
        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        #endregion

        /// <summary>
        /// Handles the BeginRequest event of the context control.
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
        private void context_BeginRequest(object sender, EventArgs e)
        {
            HttpContext context = (sender as HttpApplication).Context;
            string path = context.Request.Path.ToUpperInvariant();
            string url = context.Request.RawUrl.ToUpperInvariant();

            path = path.Replace(".ASPX.CS", "");
            url = url.Replace(".ASPX.CS", "");

            if (url.Contains(SubjectSettings.Instance.FileExtension.ToUpperInvariant()) && !url.Contains("ERROR404.ASPX"))
            {
                if (path == Utils.RelativeWebRoot.ToUpperInvariant() + "DEFAULT.ASPX" && context.Request.QueryString.Count == 0)
                {
                    Page front = Page.GetFrontPage();
                    if (front != null)
                        url = front.RelativeLink.ToUpperInvariant();
                }

                if (url.Contains("/POST/"))
                {
                    RewritePost(context, url);
                }
                else if (url.Contains("/CATEGORY/"))
                {
                    RewriteCategory(context, url);
                }
                else if (url.Contains("/PAGE/"))
                {
                    RewritePage(context, url);
                }
                else if (url.Contains("/CALENDAR/"))
                {
                    context.RewritePath(Utils.RelativeWebRoot + "default.aspx?calendar=show", false);
                }
                else if (url.Contains("/DEFAULT" + SubjectSettings.Instance.FileExtension.ToUpperInvariant()))
                {
                    RewriteDefault(context);
                }
                else if (url.Contains("/AUTHOR/"))
                {
                    string author = ExtractTitle(context, url);
                    context.RewritePath(Utils.RelativeWebRoot + "default" + SubjectSettings.Instance.FileExtension + "?name=" + author + GetQueryString(context), false);
                }
                else if (path.Contains("/BLOG.ASPX"))
                {
                    context.RewritePath(Utils.RelativeWebRoot + "default.aspx?blog=true" + GetQueryString(context));
                }
            }
        }

        
        private static void RewritePost(HttpContext context, string url)
        {/*
            DateTime date = ExtractDate(context);
            string slug = ExtractTitle(context, url);
            Post post = Post.Posts.Find(delegate(Post p)
            {
                if (date != DateTime.MinValue && (p.DateCreated.Year != date.Year || p.DateCreated.Month != date.Month))
                {
                    if (p.DateCreated.Day != 1 && p.DateCreated.Day != date.Day)
                        return false;
                }

                return slug.Equals(Utils.RemoveIllegalCharacters(p.Slug), StringComparison.OrdinalIgnoreCase);
            });

            if (post != null)
            {
                if (url.Contains("/FEED/"))
                {
                    context.RewritePath(Utils.RelativeWebRoot + "syndication.axd?post=" + post.Id.ToString() + GetQueryString(context), false);
                }
                else
                {
                    context.RewritePath(Utils.RelativeWebRoot + "post.aspx?id=" + post.Id.ToString() + GetQueryString(context), false);
                }
            }
        */}

        private static void RewriteCategory(HttpContext context, string url)
        {/*
            string title = ExtractTitle(context, url);
            foreach (Category cat in Category.Categories)
            {
                string legalTitle = Utils.RemoveIllegalCharacters(cat.Title).ToLowerInvariant();
                if (title.Equals(legalTitle, StringComparison.OrdinalIgnoreCase))
                {
                    if (url.Contains("/FEED/"))
                    {
                        context.RewritePath(Utils.RelativeWebRoot + "syndication.axd?category=" + cat.Id.ToString() + GetQueryString(context), false);
                    }
                    else
                    {
                        context.RewritePath(Utils.RelativeWebRoot + "default.aspx?id=" + cat.Id.ToString() + GetQueryString(context), false);
                        break;
                    }
                } 
            }
        */}
        

        private static void RewritePage(HttpContext context, string url)
        {
            string slug = ExtractTitle(context, url);
            Page page = Page.Pages.Find(p => slug.Equals(Utils.RemoveIllegalCharacters(p.Slug), StringComparison.OrdinalIgnoreCase));

            if (page != null)
            {
                context.RewritePath(Utils.RelativeWebRoot + "page.aspx?id=" + page.Id + GetQueryString(context), false);
            }
        }

        private static readonly Regex YEAR = new Regex("/([0-9][0-9][0-9][0-9])/", RegexOptions.IgnoreCase | RegexOptions.Compiled);
        private static readonly Regex YEAR_MONTH = new Regex("/([0-9][0-9][0-9][0-9])/([0-1][0-9])/", RegexOptions.IgnoreCase | RegexOptions.Compiled);
        private static readonly Regex YEAR_MONTH_DAY = new Regex("/([0-9][0-9][0-9][0-9])/([0-1][0-9])/([0-3][0-9])/", RegexOptions.IgnoreCase | RegexOptions.Compiled);

        private static void RewriteDefault(HttpContext context)
        {
            string url = context.Request.RawUrl;
            string page = "&page=" + context.Request.QueryString["page"];
            if (string.IsNullOrEmpty(context.Request.QueryString["page"]))
                page = null;

            if (YEAR_MONTH_DAY.IsMatch(url))
            {
                Match match = YEAR_MONTH_DAY.Match(url);
                string year = match.Groups[1].Value;
                string month = match.Groups[2].Value;
                string day = match.Groups[3].Value;
                string date = year + "-" + month + "-" + day;
                context.RewritePath(Utils.RelativeWebRoot + "default.aspx?date=" + date + page, false);
            }
            else if (YEAR_MONTH.IsMatch(url))
            {
                Match match = YEAR_MONTH.Match(url);
                string year = match.Groups[1].Value;
                string month = match.Groups[2].Value;
                string path = string.Format("default.aspx?year={0}&month={1}", year, month);
                context.RewritePath(Utils.RelativeWebRoot + path + page, false);
            }
            else if (YEAR.IsMatch(url))
            {
                Match match = YEAR.Match(url);
                string year = match.Groups[1].Value;
                string path = string.Format("default.aspx?year={0}", year);
                context.RewritePath(Utils.RelativeWebRoot + path + page, false);
            }
            else
            {
                context.RewritePath(url.Replace("Default.aspx", "default.aspx")); // fixes a casing oddity on Mono
            }

        }

        /// <summary>
        /// Extracts the title from the requested URL.
        /// </summary>
        private static string ExtractTitle(HttpContext context, string url)
        {
            url = url.ToLowerInvariant().Replace("---", "-");
            if (url.Contains(SubjectSettings.Instance.FileExtension) && url.EndsWith("/"))
            {
                url = url.Substring(0, url.Length - 1);
                context.Response.AppendHeader("location", url);
                context.Response.StatusCode = 301;
            }

            url = url.Substring(0, url.IndexOf(SubjectSettings.Instance.FileExtension));
            int index = url.LastIndexOf("/") + 1;
            string title = url.Substring(index);
            return context.Server.UrlEncode(title);
        }

        /// <summary>
        /// Extracts the year and month from the requested URL and returns that as a DateTime.
        /// </summary>
        private static DateTime ExtractDate(HttpContext context)
        {
            if (!SubjectSettings.Instance.TimeStampPostLinks)
                return DateTime.MinValue;

            Match match = YEAR_MONTH_DAY.Match(context.Request.RawUrl);
            if (match.Success)
            {
                int year = int.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture);
                int month = int.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture);
                int day = int.Parse(match.Groups[3].Value, CultureInfo.InvariantCulture);
                return new DateTime(year, month, day);
            }

            match = YEAR_MONTH.Match(context.Request.RawUrl);
            if (match.Success)
            {
                int year = int.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture);
                int month = int.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture);
                return new DateTime(year, month, 1);
            }

            return DateTime.MinValue;
        }

        /// <summary>
        /// Gets the query string from the requested URL.
        /// </summary>
        /// <param name="context">The context.</param>
        /// <returns></returns>
        private static string GetQueryString(HttpContext context)
        {
            string query = context.Request.QueryString.ToString();
            if (!string.IsNullOrEmpty(query))
                return "&" + query;

            return string.Empty;
        }
    }
}
